Implications for assessing the association between maternal anaemia and postpartum haemorrhage
Authors: Md Nuruzzaman Khan
Journal: The Lancet Global Health (2023)

Postpartum haemorrhage is a severe condition characterised by heavy bleeding following childbirth, typically within 24 h, and is a leading cause of maternal and child mortality in low-income and middle-income countries (LMICs).1Ngwenya S Postpartum hemorrhage: incidence, risk factors, and outcomes in a low-resource setting.Int J Women's Health. 2016; 8: 647-650Crossref PubMed Scopus (0) Google Scholar Additionally, it heightens the likelihood of negative outcomes for newborns, such as premature birth and low birthweight.2Wormer KC Jamil RT Bryant SB Acute postpartum hemorrhage. StatPearls Publishing, Tampa, FL2022Google Scholar The primary cause of postpartum haemorrhage is uterine atony.2Wormer KC Jamil RT Bryant SB Acute postpartum hemorrhage. StatPearls Publishing, Tampa, FL2022Google Scholar, 3Amanuel T Dache A Dona A Postpartum hemorrhage and its associated factors among women who gave birth at Yirgalem General Hospital, Sidama Regional State, Ethiopia.Health Serv Res Manag Epidemiol. 2021; 8 (23333928211062777)PubMed Google Scholar Insufficient access to skilled health-care providers and inadequate quality of obstetric care further contribute to the high prevalence of postpartum haemorrhage in LMICs.1Ngwenya S Postpartum hemorrhage: incidence, risk factors, and outcomes in a low-resource setting.Int J Women's Health. 2016; 8: 647-650Crossref PubMed Scopus (0) Google Scholar Comprehensively exploring all potential risk factors in order to effectively reduce the occurrence of postpartum haemorrhage is crucial. The study in The Lancet Global Health by the WOMAN-2 trial collaborators4The WOMAN-2 trial collaboratorsMaternal anaemia and the risk of postpartum haemorrhage: a cohort analysis of data from the WOMAN-2 trial.Lancet Glob Health. 2023; (published online June 27.)https://doi.org/10.1016/S2214-109X(23)00245-0Google Scholar investigates the association between moderate and severe anaemia and postpartum haemorrhage in women who have given birth vaginally. Although this research offers valuable insights regarding the association between anaemia during pregnancy and postpartum haemorrhage, similar to previous studies,5Shi H Chen L Wang Y et al.Severity of anemia during pregnancy and adverse maternal and fetal outcomes.JAMA Network Open. 2022; 5e2147046-eCrossref Scopus (17) Google Scholar, 6Nair M Choudhury MK Choudhury SS et al.Association between maternal anaemia and pregnancy outcomes: a cohort study in Assam, India.BMJ Global Health. 2016; 1e000026Crossref Scopus (65) Google Scholar, 7Daru J Zamora J Fernández-Félix BM et al.Risk of maternal mortality in women with severe anaemia during pregnancy and post partum: a multilevel analysis.Lancet Glob Health. 2018; 6: e548-e554Summary Full Text Full Text PDF PubMed Scopus (171) Google Scholar there are several challenges that raise concerns about the generalisability of the findings of this study. The study was done in four LMICs: Pakistan, Nigeria, Tanzania, and Zambia. However, it is important to note that the distribution of data was uneven, with 8751 (82·9%) of 10 561 women recruited from Pakistan. This over-representation of data from Pakistan suggests that the findings are more likely to reflect the situation in Pakistan rather than in the other three countries. This disparity could be attributed to variations in sociodemographic and health-related factors at the country level, which are evident in the study samples, and can influence the reported association between maternal anaemia and postpartum haemorrhage. Furthermore, this study only included women who gave birth vaginally in health-care facilities without considering the variations in the availability and accessibility of maternal health-care services across these four countries, despite evidence of significant variations.8Haakenstad A Yearwood JA Fullman N et al.Assessing performance of the Healthcare Access and Quality Index, overall and by select age groups, for 204 countries and territories, 1990–2019: a systematic analysis from the Global Burden of Disease Study 2019.Lancet Glob Health. 2022; 10: e1715-e1743Summary Full Text Full Text PDF PubMed Scopus (9) Google Scholar Additionally, in many LMICs, including the countries in the study, the majority of vaginal births occur at home, and health-care facility births are primarily done through caesarean section.9Boatin AA Ngonzi J Ganyaglo G Mbaye M Wylie BJ Diouf K Cesarean delivery in low-and middle-income countries: a review of quality of care metrics and targets for improvement.Semin Fetal Neonatal Med. 2021; 26101199Summary Full Text Full Text PDF PubMed Scopus (4) Google Scholar This is influenced by social and religious customs regarding accessing delivery health-care services, lack of awareness regarding the importance of accessing delivery health-care services, and the capacity of health-care facilities to provide such services.9Boatin AA Ngonzi J Ganyaglo G Mbaye M Wylie BJ Diouf K Cesarean delivery in low-and middle-income countries: a review of quality of care metrics and targets for improvement.Semin Fetal Neonatal Med. 2021; 26101199Summary Full Text Full Text PDF PubMed Scopus (4) Google Scholar Such considerations present two additional challenges. Firstly, women admitted to hospitals who underwent caesarean section delivery were excluded from the study, potentially introducing a selection bias.10Khan MN Islam MM Akter S Spatial distribution of caesarean deliveries and their determinants in Bangladesh: evidence from linked data of population and health facility survey.Lancet Regional Health-Southeast Asia. 2023; (published online Jan 31.)https://doi.org/10.1016/j.lansea.2023.100153Summary Full Text Full Text PDF Scopus (0) Google Scholar Secondly, women who opt for delivering their babies in a health-care facility through vaginal birth tend to possess a higher socioeconomic status, heightened awareness, and increased concerns regarding their pregnancy and delivery.10Khan MN Islam MM Akter S Spatial distribution of caesarean deliveries and their determinants in Bangladesh: evidence from linked data of population and health facility survey.Lancet Regional Health-Southeast Asia. 2023; (published online Jan 31.)https://doi.org/10.1016/j.lansea.2023.100153Summary Full Text Full Text PDF Scopus (0) Google Scholar These factors, coupled with a relatively lower prevalence of anaemia among women with such characteristics, can contribute to improved pregnancy management, ultimately resulting in a reduced incidence of postpartum haemorrhage when compared with women who choose to deliver at home. Moreover, an important confounding factor considered in this study, BMI, was determined using weight measured after admission to the hospital and before giving birth. If unavailable to measure during this period, weight measured during antenatal care visits was also considered. This measurement procedure introduces several risks, including overestimation of BMI due to the increased weight during pregnancy and comparing weight measurements at two different time points. In the statistical model, the authors also incorporated random effects at the site levels and a fixed effect for the country. However, it is important to note that, in LMICs, differences across health-care facilities are also prevalent, particularly between public and private sectors as well as urban and rural settings. Due to these differences, it is common for relatively affluent populations in LMICs to seek private health care for delivery services.10Khan MN Islam MM Akter S Spatial distribution of caesarean deliveries and their determinants in Bangladesh: evidence from linked data of population and health facility survey.Lancet Regional Health-Southeast Asia. 2023; (published online Jan 31.)https://doi.org/10.1016/j.lansea.2023.100153Summary Full Text Full Text PDF Scopus (0) Google Scholar These challenges could affect the strength of the association reported in this study. Additionally, this study does not provide information about the risk of postpartum haemorrhage among women who are not anaemic or have mild anaemia. This limitation hinders our understanding of the risk of postpartum haemorrhage among women with moderate and severe anaemia compared with non-anaemic women, as explored in smaller-scale studies from China and India.5Shi H Chen L Wang Y et al.Severity of anemia during pregnancy and adverse maternal and fetal outcomes.JAMA Network Open. 2022; 5e2147046-eCrossref Scopus (17) Google Scholar, 6Nair M Choudhury MK Choudhury SS et al.Association between maternal anaemia and pregnancy outcomes: a cohort study in Assam, India.BMJ Global Health. 2016; 1e000026Crossref Scopus (65) Google Scholar Moreover, the estimation of likelihood of death was based on a mere 14 deceased women, rendering it less precise. Additionally, this estimation fails to provide insights into the risk of maternal mortality among women with anaemia compared with women without anaemia. This understanding holds importance for evidence-based policy formulation. Given the persistent challenges of anaemia and postpartum haemorrhage in LMICs, it is imperative to conduct future cohort studies that encompass all women from the onset of pregnancy, regardless of the place of delivery, while incorporating a comprehensive array of accurately measured confounding factors. I declare no competing interests. Maternal anaemia and the risk of postpartum haemorrhage: a cohort analysis of data from the WOMAN-2 trialAnaemia is strongly associated with postpartum haemorrhage and the risk of death or near miss. Attention should be given to the prevention and treatment of anaemia in women of reproductive age. Full-Text PDF Open Access